Ventilation system

ABSTRACT

A ventilation system comprising ducts for injecting air into and exhausting air from a room, said ducts being separated by a partition incorporating an opening between the ducts in which a heat conducting damper plate, both surfaces of which are provided with coatings of an insulating material, is movably arranged to adjust the ventilation. The insulating coating of the surface facing the injected air flow covers the plate completely absent from a peripheral area of the part of the plate located in the injection duct, whereas the coating on the opposite surface covers the part of the plate located in said injection duct right to the peripheral edge of the plate and leaves the part of the plate located in the exhaust duct uncovered.

United States Patent [191 Holt et al. Nov. 12, 1974 VENTILATION SYSTEM 3,487,767 1/1970 Kristiansen 98/33 R 19 "l [75] Inventors: Jorgen Holt, Naestved; Christian 3 750 557 8/ 73 98/33 Videmark, Haslev; Palle Hein 1 Christiansen, Naestved, all of Primary -W Wye Denmark Attorney, Agent, or FzrmSughrue, Rothwell, Mion,

Zinn & Macpeak [73] Assignee: Nordisk Ventilator C0., A/S,

I Naestved, Denmark ABSTRACT [22] Filed June 1973 A ventilation system comprising ducts for injecting air [2l] Appl. No.: 367,906 into and exhausting air from a room, said ducts being separated by a partition incorporating an opening between the ducts in which a heat conducting damper [30] Forelgn Apphcatmn Pnomy Data plate, both surfaces of which are provided with coat- June 9, 1972 Denmark 2914/72 ings of an insulating material, is movably arranged to adjust the ventilation. The insulating coating of the [52] US, Cl. 98/33, 98/41 surface facing the injected air l covers the plate [5 l] Int. Cl F24f 13/00 completely absent from a peripheral area} of the part [58] Fleld 0f Search 98/33 R, 33 A, 41 of the plate located in the injection duct whereas the coating on the opposite surface covers the part of the References C'ted plate located in said injection duct right to the periph- UNITED S AT PATENTS eral edge of the plate and leaves the part of the plate 2,732,027 1/1956 Wallin 98/33 R located in the exhaust duct uncovered. 3,122,307 2/l964 Wasson .t 98/33 R 3,463,391 8/1969 Halgans 98/33 R 2 Clalms, 4 Drawlng Flglres c r S a, a

11v 6 7 I/ a IIIIIIIIIIIA FIG. 1

PATENTEUNHY 12 mm mm a F 2 3,847,065

m 45 III] VENTILATION SYSTEM The present invention relates to a ventilation system comprising a duct for the injection of fresh air and a duct for the exhaustion of air from a ventilated room, said ducts extending at least on part of their length side by side separated by a common flat partition which incorporates an opening between the ducts, in which a damper member is arranged to be movable between two extreme positions, in one of which it closes said opening and in the other of which positions it blocks both ducts and opens up for complete recirculation of air exhausted from the room back to the room through the injection duct.

Ventilation systems of this kind are used, for example, in the ventilation of stables or barns and as a result of the movable damper member it is possible to adjust the ventilation in dependence on the temperature conditions in the room between full supply of fresh air and complete recirculation of return air from the ventilated room.

It is known to provide for an automatical adjustment of the ventilation by controlling the movement of a damper member by means of a thermostatecontrolled hydraulic motor in such a manner that the damper member may occupy any position between the abovementioned extreme position.

In known ventilation systems of the kind described the outer walls of the ducts as well as the partition between the ducts and the damper member are made of metal plate such as, for example, galvanized iron plate. Such ventilation systems have shown a considerable risk for water condensation and ice formation in the ventilation ductsin periods of cold weather, particularly in the part of the system incorporating the recirculation damper member. Water condensation which may occur on the walls of the ducts as well as on the damper member has the effect that dust and dirt which in the ventilation of stables is inevitably carried along by the return air through the exhaust duct adhere to and remain applied to the surfaces in question as a solid layer which may be very difficult to remove. Furthermore, in winter periods there is a risk for ice formation in that part of the duct, in which the hot, moist return air meets the cold air supplied from the ambient, i.e. on the damper member and the part of the wall of the injection duct situated opposite to the damper member. Dust coatings as well as ice formations reduce to a considerable degree the movability of the damper member and may result in a complete blocking of the damper movement. Furthermore, water condensation in the injection duct may result in water dripping into the ventilated room, which in case of a stable may give rise to a serious risk for the health of the animals. I

In order to eliminate these disadvantages and reduce the risk of water condensation it has been proposed to heat-insulate the ducts either by coating metallic tubes with an insulating layer or by manufacturing the ducts and the partition separating the ducts completely of a heat insulating and shape-keeping material. However, at low temperatures below 5C even this measure will not be sufficient to prevent freezing of the damper member relative to the partition, for which reason it is usually necessary in known ventilation systems to heat the duct on this critical place by means of, for example, electrical heating members in order to secure the reliability of the system at low temperatures.

- provided, comprising a duct for the injection of fresh air and a duct for the exhaustion of air from a ventilated room, said ducts extending at least on part of their length side by side, a common flat partition separating said ducts on said part of their length and incorporating an opening between said ducts and a damper member which is arranged in said opening to be movable be-' tween two extreme position in one of which it .closes said opening and in the other of which it blocks both ducts and opens up for complete recirculation of air exhausted from the room back to the room through the injection duct, said damper member consisting of a damper plate of a material of high heat conductivity and coatings of insulating material applied to both surfaces of said plate, the coating on the surface facing the injected air flow covering said plate completely absent from an area along the peripheral edge of the part of the damper plate located in the injection duct and the coating on the opposite surface of said damper plate covering said part of the plate located in the injection duct right to said peripheral edge and leaving the part of the plate located in the exhaust duct uncovered.

Thus, the heat conducting damper plate,which may be of aluminium, is free from insulating material on the surface of the part of the plate located in the exhaust duct, which in the recirculation position of the damper member faces the ventilated room, so that said surface is directly contacted by the hot return air passing up through the exhaustduct. The heat thereby applied to the damper plate is conveyed through the heat conducting material of said plate to the other area of the plate which is free from insulating material, i.e., the extreme peripheral area of the surface of the part of the plate located in the injection duct which faces the injected air flow, i.e., the cold ambient air. Thereby, the latter area of the damper plate at which a particularly great risk of ice formation exists will attain a higher temperature, so that this risk is materially reduced.

Experience has shown that as a result of this measure the damper movement in a ventilation system according to the invention may take place in an unrestricted manner down to temperatures below 25C.

In the following the invention is further explained with reference to the accompanying drawings, in which FIG. 1 shows an embodiment of a ventilation system according to the invention,

FIG. 2 is a cross-sectional view of a damper member used in the system shown in FIG. 1,

FIG. 3 shows the damper member shown in FIG. 2 seen from the upper side, and

FIG. 4 shows the damper member seen from the lower side.

FIG. 1 shows a ventilation system of the kind described in copending U.S. Pat. application Ser. No. 268,955 filed July 5, 1972 in the names of Jorgen Holt and Hans Christian Hansen. In the room 1 which is to be ventilated, for example, a stable a fan section 2 is arranged comprising an axial flow fan having two me chanically interconnected sets of fan blades of opposite directions of flow, said blade sets being located in a central ventilation duct and a surrounding annular duct, respectively. A fan of this construction is described in U.S. Pat. No. 3,487,767 to S. H. Kristiansen.

The two concentric ventilation ducts of the axial flow fan is connected through a connection section 3, the detailed construction of which is described in the above-mentioned patent application Ser. No. 268,955, with a twin-duct designated as a whole by the reference numeral 4 and comprising two substantially semicylindrical ducts 6 and 7 connected to the central duct and the outer annular duct of the axial flow fan, respectively, and being separated by a common flat partition 5. The twinduct 4 extends from the ventilated room 1 through the over-lying part of the building and terminates above the roof 8 thereof in a roof hood 9, which is designed with separate air passages for connecting the ducts 6 and 7, respectively, with the ambient air.

For the purpose of adjusting the ventilation in dependence on the temperature conditions the partition has an opening in which a control damper member 10 is arranged, said damper member being movable between two extreme positions in one of which the opening in the partition is closed, so that a complete supply of fresh air to room 1 is obtained, whereas in the other extremc position the damper member extends transversely of the ducts 6 and 7, whereby the supply of fresh air is blocked and complete recirculation of the exhaust air from duct 6 to duct 7 is established, such as described in the above-mentioned patent application Ser. No. 268,955.

To facilitate shipping of the ventilation system from the manufacturer to the place of installation the twinduct 4 of the embodiment shown consists of a number of shorter duct sections 11, 12, 13 and 14 which only after arrival at the place of installation is assembled in extension of each other to form the complete twinduct.

FIGS. 2 to 4 of the drawings show the damper member 10 arranged in duct section 13 in a cross-sectional view and seen from the upper side and the lower side, respectively. In accordance with the invention the damper member 10 consists of a damper plate 15 of a material of high heat conductivity such as, for example, aluminium, said plate being provided on both sides with coatings of an insulating material 16 and 17, respectively. As shown in FIG. 3, the coating 16 on the side ofdamper plate 15 facing the injected air flow, i.e., the side which in the injection duct 7 is contacted by the air supplied from the ambient, covers damper plate 15 completely absent from an area 18 along the extreme peripheral edge of that part of the damper plate, which is located in injection duct 7. The coating 17 on the opposite side of damper plate 15 which faces the ventilated room 1 covers only the part of the damper plate located in injection duct 7, but extends right to the peripheral edge of that part. The part of the latter side of the damper plate which is located in the exhaust duct 6 is completely free from the coating of insulating material, and in the embodiment shown the coating 17 is furthermore, such as shown in H6. 4, designed so as to cover only a substantially half-moon-shaped area of the part of the plate located in injection duct 7.

In a ventilation system according to the invention the hot, moist return air in the exhaust duct will, in the position shown of damper member 10, contact the exposed area of the heat conducting damper plate 15. As a result of the presence of insulating coatings l6 and 17 on the above-mentioned areas of the surfaces of the damper plate the heat thereby applied to damper plate 15 will be conveyed to the exposed peripheral area 18 of the surface of the part of the damper plate located in injection duct 7, which faces the injected air flow, so 7 that this peripheral area which possesses the greatest risk of water condensation and ice formation attains a relatively high temperature, whereby said risk is materially reduced. By allowing insulating coating 17 to cover only a fraction of the surface of the part of the damper plate located in injection duct 7, which faces the ventilated room, such as shown in FIG. 4, the maximum possible heat receiving surface for the heat conducting damper plate 15 is obtained.

We claim:

1. A ventilation system comprising a duct for the injection of fresh air and a duct for the exhaustion of air from a ventilated room, said ducts extending at least on part of their length side by side, a common flat partition separating said ducts on said part of their length and incorporation an opening between said ducts and a damper member which is arranged in said opening to be movable between two extreme position in one of which it closes said opening and in the other of which it blocks both ducts and opens up for complete recirculation of air exhausted from the room back to the room through the injection duct, said damper member consisting of a damper plate of a material of high heat conductivity and coatings of insulating material applied to both surfaces ofv said plate, the coating on the surface facing the injected air flow covering said plate completely absent from an area along the peripheral edge of the part of the damper plate located in the injection duct and the coating on the opposite surface of said damper plate covering said part of the plate located in the injection duct right to said peripheral edge and leaving the part of the plate located in the exhaust duct uncovered.

2. A ventilation system as claimed in claim 1, wherein said coating of insulating material on said opposite surface covers only a fraction of said part of the plate located in the injection duct, said fraction including, however, the whole peripheral edge of said part of the plate. 

1. A ventilation system comprising a duct for the injection of fresh air and a duct for the exhaustion of air from a ventilated room, said ducts extending at least on part of their length side by side, a common flat partition separating said ducts on said part of their length and incorporation an opening between said ducts and a damper member which is arranged in said opening to be movable between two extreme position in one of which it closes said opening and in the other of which it blocks both ducts and opens up for complete recirculation of air exhausted from the room back to the room through the injection duct, said damper member consisting of a damper plate of a material of high heat conductivity and coatings of insulating material applied to both surfaces of said plate, the coating on the surface facing the injected air flow covering said plate completely absent from an area along the peripheral edge of the part of the damper plate located in the injection duct and the coating on the opposite surface of said damper plate covering said part of the plate located in the injection duct right to said peripheral edge and leaving the part of the plate located in the exhaust duct uncovered.
 2. A ventilation system as claimed in claim 1, wherein said coating of insulating material on said opposite surface covers only a fraction of said part of the plate located in the injection duct, said fraction including, however, the whole peripheral edge of said part of the plate. 